 /*******************************************************************************
  * Copyright (c) 2004, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.themes;

 import org.eclipse.jface.util.IPropertyChangeListener;

 /**
  * A theme manager is an object that contains references to usable
  * <code>ITheme</code> objects and maintains a reference to the currently active
  * theme. This theme will be used by the workbench to decorate tab folders and
  * other controls where possible. The workbench implementation of this
  * interface will push the values of the current theme into the underlying jface
  * registries ({@link org.eclipse.jface.resource.ColorRegistry} and
  * {@link org.eclipse.jface.resource.FontRegistry} whenever the current theme
  * changes. Clients who do not need access to specific themes may instead
  * attach listeners to these registries directly.
  *
  * <p>
  * This interface is not intended to be implemented or extended by clients.
  * </p>
  *
  * @see org.eclipse.ui.IWorkbench#getThemeManager()
  * @since 3.0
  */
 public interface IThemeManager {

     /**
      * Indicates that the current theme has changed to a new theme.
      */
     public static final String CHANGE_CURRENT_THEME = "CHANGE_CURRENT_THEME"; //$NON-NLS-1$

     /**
      * The default theme id.
      */
     public static final String DEFAULT_THEME = "org.eclipse.ui.defaultTheme"; //$NON-NLS-1$

     /**
      * Adds a property listener to the manager. Any events fired by the
      * underlying registries of the current theme will cause an event to be
      * fired. This event is the same event that was fired by the registry.
      * As such, the "source" attribute of the event will not be this manager,
      * but rather the color or font registry. Additionally, an event is fired
      * when the current theme changes to a new theme. The "property" attribute
      * of such an event will have the value {@link IThemeManager#CHANGE_CURRENT_THEME}.
      *
      * @param listener the listener to add
      */
     void addPropertyChangeListener(IPropertyChangeListener listener);

     /**
      * Get the currently active theme.
      *
      * @return the current theme. This will never be <code>null</code>.
      */
     ITheme getCurrentTheme();

     /**
      * Get a theme.
      *
      * @param id the theme to find.
      * @return the <code>ITheme</code> or <code>null</code> if it cannot be found.
      */
     ITheme getTheme(String id);

     /**
      * Removes a property listener from the workbench.
      *
      * @param listener the listener to remove
      */
     void removePropertyChangeListener(IPropertyChangeListener listener);

     /**
      * Set the currently active theme.
      *
      * @param id the id of the new active theme
      */
     void setCurrentTheme(String id);
 }

